as in treacherous
formal
causing harm in a way that is gradual or not easily noticed
Most people with this insidious disease have no idea that they are infected. an insidious enemy
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Recent Examples of insidious
What makes this deal particularly insidious is the trade-off at its core.
—
Joe Wilkins, Futurism, 10 June 2026
But most of its failures are subtler, more insidious.
—Katy Waldman, New Yorker, 10 June 2026
But there is an insidious quality.
—Rory McDonald, Fortune, 6 June 2026
Best known for comedy series like Community (2009-15) and GLOW (2017-19), Alison Brie is taking on the role of Evil-Lyn, an insidious enchantress who serves as Skeletor’s main accomplice.
—Keith Langston, PEOPLE, 6 June 2026
See All Example Sentences for insidious
Joe Wilkins, Futurism, 10 June 2026
But most of its failures are subtler, more insidious.
—Katy Waldman, New Yorker, 10 June 2026
But there is an insidious quality.
—Rory McDonald, Fortune, 6 June 2026
Best known for comedy series like Community (2009-15) and GLOW (2017-19), Alison Brie is taking on the role of Evil-Lyn, an insidious enchantress who serves as Skeletor’s main accomplice.
—Keith Langston, PEOPLE, 6 June 2026
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
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This has significantly weakened the Indian rupee against the dollar at a time when global oil prices are rising, creating a treacherous situation for India, which imports more 85% of its crude requirements.—
Priyanka Salve,
CNBC,
9 June 2026
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Dunn and the clinic’s vaccinator, Moses Yambie, then took a motorbike 30 miles across a treacherous route at night to transport the infant to the nearby hospital.—
Imani Cruzen,
Twin Cities,
7 June 2026
Adjective
-
Star power takes a neutral cat-eye base and turns it into a subtle statement moment.—
Amanda Le,
InStyle,
17 June 2026
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Where their Florida style is bold and flamboyant, the ranch is subtle and defined by a rich, earthy palette.—
Elizabeth Kiefer,
Architectural Digest,
17 June 2026
Adjective
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Baldoni denied the allegations and maintained that Lively's claims were false.—
Janelle Ash , Lauryn Overhultz,
FOXNews.com,
13 June 2026
-
Baldoni filed a countersuit in January 2025 for civil extortion, defamation and false light.—
Liza Esquibias,
USA Today,
12 June 2026
Adjective
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The suit alleges the group, known widely as WPATH, made deceptive claims about gender-affirming care for minors and that its members profited off the claims.—
ABC News,
ABC News,
17 June 2026
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Grand Canyon’s rim-to-river routes can be deceptive because the steepest physical test comes on the way out, after hikers have descended into hotter terrain, experts say.—
Jessica Mekles,
FOXNews.com,
15 June 2026
Adjective
-
This is perhaps the most perfidious practice of this sort of politics.—
David M. Drucker,
Twin Cities,
3 June 2026
-
Pakistan was a perfidious ‘ally’ in Afghanistan, backing the Taliban while pretending to be our friends.—
Efrat Lachter,
FOXNews.com,
18 Apr. 2026
Adjective
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The researchers calculated welfare losses from incorrect beliefs could potentially reach up to 43% of the initial loan balance in the most extreme cases, translating to roughly $21,500 on the median borrower’s $50,000 in debt.—
Catherina Gioino,
Fortune,
17 June 2026
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For example, many borrowers are getting incorrect estimates of what their bill would be on IBR, Rodriguez said.—
Annie Nova,
CNBC,
16 June 2026
Adjective
-
But the truth may be that Anthropic is wrong about Mythos’ dangers, and that the government is taking a drastic action that could potentially hurt the US in the technology race with China.—
Reed Albergotti,
semafor.com,
13 June 2026
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But it was soon revealed that the actors were given the wrong envelope by accountants from Pricewaterhouse Coopers, the firm charged with counting Oscar votes, keeping the results secret and organizing and handing out envelopes to presenters.—
Tribune News Service,
Baltimore Sun,
13 June 2026
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 20 Jun. 2026.
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